I also read a breakdown of the touch screen scan rate (the refresh rate at which touch gestures are captured), which was significantly faster for ios devices. That also contributed to the difference in feel. Do you know if android devices have "caught up?"

I think you might be interested in this:

http://forum.xda-developers.com/showthread.php?t=2706200

I have had an S3, iPhone 5, and HTC One (M7) and the iPhone 5 definitely felt the smoothest, but now I'm interested in seeing if the M8 really has leveled the playing field.

The scan rate isn't typically the worst factor, which is usually between 120-300hz (meaning a max additional latency of 3 - 30ms), but rather deriving meaning from that data is. Filtering in a noise-free environment typically adds a few scan frames of latency, which is what puts devices in the 60-120ms of latency, and a noisy environment (i.e. plugged in to a cheap charger) can easily up that to a few hundred ms of latency.

> The perceived sluggishness of Android was down to how the system was architected, especially around the way the UI thread was prioritised

UI thread priority has been debunked time and time again: https://plus.google.com/105051985738280261832/posts/XAZ4CeVP...

Even if it hadn't been, what evidence is there that it would require a ground up redesign?

The UI thread doesn't get any special treatment on iOS, so unless Android is deprioritizing its UI thread, it doesn't seem likely that this would be a problem.

Doesn't get any special treatment by Android either. All other threads get set to background priority (well, most, but all that we care about), which by default can only consume 10% of CPU resources.